Montesquieu never referred to Persian Letters as a novel until "Quelques remarques sur les Lettres persanes (1757)," which begins: "Nothing found more favor in Lettres persanes than to discover in them, unexpectedly, a sort of novel. One sees the beginning, the development, and the end; the various characters are placed in a chain that connects them." Initially, for most of its first readers as well as for its author, the book was not thought of primarily a novel, and even less an "epistolary novel" (as it is often classified now), which was not at that time in any sense a constituted genre. Indeed, it has little in common with the sole model at the time, Guilleragues's Lettres portugaises of 1669. A collection of "letters" in 1721 would more likely evoke the recent tradition of essentially polemical and political periodicals, such as Lettres historiques (1692–1728) or the Jesuits' famous Lettres édifiantes et curieuses (1703–1776), not to mention Mme Dunoyer's Lettres historiques et galantes (1707–1717) which, in the form of a correspondence between two women, provide a chronicle of the end of the reign of Louis XIV and the beginning of the Regency. Lettres persanes thus helped confirm the vogue of a format that was already more or less established. It is in its numerous imitations – such as Lettres juives (1738) and Lettres chinoises (1739) of Boyer d’Argens, Lettres d’une Turque à Paris, écrites à sa sœur (1730) by Poullain de Saint-Foix (published several times in conjunction with Lettres persanes), and perhaps especially Françoise de Graffigny’s Lettres d’une Péruvienne (1747) – not to mention the letter-novels of Richardson – which, between 1721 and 1754, had in effect transformed Lettres persanes into an "epistolary novel". Whence this remark in Montesquieu's Mes Pensées: "My Lettres persanes taught people to write letter-novels" (no. 1621).
The epistolary structure is quite flexible, nineteen correspondents in all, with at least twenty-two recipients. Usbek and Rica by far dominate with sixty-six letters for the former and forty-seven for the latter (of the original 150). Ibben functions more as addressee than correspondent, writing only two letters but the recipient of forty-two. An unnamed person designated only as *** (if always the same) receives eighteen letters but writes none at all. There is even a particular anomaly, a letter from Hagi Ibbi to Ben Josué (Letter 37 [39]), neither of whom is mentioned anywhere else.
The letters are all dated in accordance with a lunar calendar which, as Robert Shackleton showed in 1954, in fact corresponds to our own by simple substitution of Muslim names as follows: Zilcadé (January), Zilhagé (February), Maharram (March), Saphar (April), Rebiab I (May), Rebiab II (June), Gemmadi I (July), Gemmadi II (August), Rhegeb (September), Chahban (October), Rhamazan (November), Chalval (December).
